Electronic part producing method and electronic part

ABSTRACT

A conductor portion is formed on the surface of a support member. After the conductor portion is formed, a copper foil on which resin is attached is moved downward from above the conductor portion to pressurize the conductor portion while covering it. the copper foil with the resin is pressed to the height of the conductor potion while using the conductor portion as a stopper. Thus, it is possible to make the height of the insulating layer equal to the height of the conductor portion.

TECHNICAL FIELD

The present invention relates to an electronic part and a method formanufacturing an electronic part having a multilayer structure, and moreparticularly, to an electronic part and a method for manufacturing anelectronic part with which the thickness of each layer can be adjustedreliably.

BACKGROUND ART

Electronic parts and printed wiring boards in which wiring patterns areformed on insulating layers and the wiring patterns are stacked alongtheir thickness direction to form a multilayer structure have beenknown.

Various methods for manufacturing such structures have been proposed ordisclosed. FIGS. 3A and 3B are process diagrams illustrating aconventional process of producing each layer of an electronic part.

In the process shown in FIG. 3A, the surface of an insulating layer 1 isirradiated with a laser so as to be perforated. After a hole 2 is formedby the laser processing, the hole 2 is filled with paste, or a conductorportion in the form of a film or a column is formed in the hole 2.

In the process shown in FIG. 3B, a conductor portion 4 is formed byplating or etching on an insulating layer 3, which has been formed inadvance. After the conductor portion 4 is formed by the above processes,an insulating resin 5 is applied on the surface of the conductor portion4 by spin coating (see, for example, patent document 1).

In a different known method, a bump of an electrically conductive pasteis formed on wiring on a board, then an interlaminate connectioninsulating material and a metal layer are provided, and the bump iscaused to penetrate a molded resin by a pressing process to achieveelectrical connection between said bump and the metal layer (see, forexample, patent document 2).

Furthermore, a method of forming a via hole conductor by forming athrough hole by means of a carbon dioxide gas laser or other means andfiling the through hole with paste containing powder of a low resistancemetal such as gold, silver, copper and aluminum has also been disclosed(see, for example, patent document 3).

-   -   Patent Document 1: Japanese Patent Application Laid-Open No.        10-22636.    -   Patent Document 2: Japanese Patent Application Laid-Open No.        2002-137328.    -   Patent Document 3: Japanese Patent Application Laid-Open No.        2002-134881.

In connection with electronic parts having a multilayer structure,incorporation of an element etc. in the interior of the electronic parthas been considered in order to further increase density and functions.If an element such as a passive component is to be formed between wiringpatterns stacked along the lamination direction, the distance betweenthe aforementioned wiring patterns is an important factor thatdetermines characteristics of the aforementioned element. Accordingly,from the viewpoint of stabilization of the element characteristics, amethod for manufacturing an electronic part that enables reliablecontrol of the distance between the aforementioned wiring patterns orthe thickness of each layer in the aforementioned electronic part hasbeen demanded.

Nevertheless, in the above-mentioned manufacturing method shown in FIG.3A, a conductor portion is simply formed in a hole 2 formed on aninsulating layer 1 by a laser processing, but the overall thickness ofthe layers is not controlled.

In the manufacturing method shown in FIG. 3B, an insulating resin layeris formed to cover conductor portions by applying resin by spin coating.However, undulation is created on the surface of the insulating resindue to presence of the conductor portions 4, and therefore it isdifficult to make the overall thickness of the layers uniform.

Furthermore, in the method in which a bump of electrically conductivepaste is formed on wiring on a board and then the bump is caused topenetrate a molded resin by pressing, no consideration has been made oncontrol of the overall thickness of the layers. Still further, JapanesePatent Application Laid-Open No. 2002-134881 only teaches to form a viahole conductor by filling paste, but no consideration is made on controlof the overall thickness of the layers.

DISCLOSURE OF THE INVENTION

The present invention has been made in view of the above-describedproblems of the prior arts. An object of the present invention is toprovide a method for manufacturing an electronic part with which thelayer thickness can be controlled reliably, and to provide an electronicpart manufacture using that method.

The present invention has been made based on the finding that when aconductor portion is formed on the surface of a support member and aninsulating member is pressed against the conductor portion from abovewhile using the conductor portion as a stopper, the thickness of theinsulating member will be made equal to the height of the conductorportion, so that unevenness (or undulation) can be suppressed to theminimum and a layer having a uniform thickness can be formed.

In the method for manufacturing an electronic part according to thepresent invention, a layer having a uniform thickness is formed byforming a conductor portion on a surface of a support member, bringingan insulating sheet into contact with said conductor portion from above,and pressing said insulating sheet to the height of said conductorportion using said conductor portion as a stopper to make the height ofsaid insulating sheet equal to the height of said conductor portion.

Alternatively, a layer having a uniform thickness is formed by forming aconductor portion on a surface of a support member, bringing aninsulating sheet into contact with said conductor portion from above,pressing said insulating sheet to the height of said conductor portionusing said conductor portion as a stopper to make the height of saidinsulating sheet equal to the height of said conductor portion, and thendetaching said conductor portion and said insulating sheet from saidsurface.

More specifically, a layer having a uniform thickness is formed byforming a power supply film on a surface of a support member, forming aconductor portion by plating using the power supply film as anelectrode, bringing an insulating sheet into contact with said conductorportion from above, pressing said insulating sheet to the height of saidconductor portion using said conductor portion as a stopper to make theheight of said insulating sheet equal to the height of said conductorportion, then detaching said conductor portion and said insulating sheetfrom said surface, and removing said power supply film.

It is preferred that a B-stage sheet or a thermoplastic sheet be used assaid insulating sheet.

An electronic part according to the present invention comprises, atleast, a conductor portion having an interior completely filled up andrising from vertically from a surface of a support member and aninsulating layer surrounding the circumference of said conductor portionand having a thickness equal to said conductor portion, wherein saidconductor portion and said insulating layer form a layer having auniform thickness.

Alternatively, an electronic part according to the present inventioncomprises, at least, a conductor portion having an interior completelyfilled up and rising from vertically from the bottom of a support memberand an insulating layer surrounding the circumference of said conductorportion and having a thickness equal to said conductor portion, saidconductor portion and said insulating layer forming a layer having auniform thickness. It is preferred that said conductor portion be formedby plating.

According to the above-described features, a conductor portion isfirstly formed on the surface of a support member that can be detached.The conductor portion may be formed by, for example, plating using apower supply film. When the conductor portion is formed by plating, thecircumferential surface of the conductor portion rises substantiallyvertically from said insulating layer. Accordingly, it is possible toeliminate changes in the diameter between the top portion and the bottomportion of the conductor portion. In addition, it is possible to makethe interior of the conductor member solid. Therefore, it is possible tomake the resistivity of the conductor portion low and to enhance theheat radiation effect.

After the conductor portion has been formed on the surface of theinsulating layer, an insulating sheet is brought into contact with theconductor portion from above so that the conductor portion is covered bythe insulating sheet, and the insulating sheet is pressurized (andheated) from above. With the application of the pressure, the conductorportion dents into the insulating sheet with deformation of theinsulating sheet. The pressurizing means uses the conductor portion as astopper to stop pressurizing when the insulating sheet comes in contactwith said conductor portion. Thus, the thickness of the insulating sheetcan be made equal to the height of the conductor portion. The insulatingsheet is cured while maintaining this state, so that the insulatingsheet becomes an insulating layer. Thus, a uniform layer thickness canbe realized irrespective of presence/absence of the conductor portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B and 1C are schematic process diagrams for illustrating amethod for manufacturing an electronic part according to an embodiment.

FIGS. 2A, 2B and 2C are schematic process diagrams for illustrating themethod for manufacturing an electronic part according to the embodiment.

FIGS. 3A and 3B are process diagrams showing a conventional process formanufacturing each layer of an electronic part.

THE BEST MODE FOR CARRYING OUT THE INVENTION

In the following, a preferred, specific embodiment of the method formanufacturing an electronic part according to the present invention willbe described in detail.

FIGS. 1A to 1C and 2A to 2C schematic process diagrams for illustratingan embodiment of the method of manufacturing an electronic partaccording to the present invention.

In producing an electronic part by the manufacturing method of thisembodiment, a support member 10 that can be detached from the part isprepared as shown in FIG. 1A; the support member is set with the surface12 for forming the electronic part facing upwardly. After the supportmember 10 is set, conductor portions 14 are formed on the aforementionedsurface 12 as shown in FIG. 1B. It will be apparent that theconfiguration of the conductor portion 14 standing on the aforementionedsurface 12 is the same as the configuration of the aforementionedconductor portion 14 standing on the bottom face of the body of thepart, since the surface 12 and the bottom face of the body of the partformed on this surface 12 are in close contact with each other. Thecharacteristics of the aforementioned support member 10 are selected inaccordance with the specification of the electronic part formed on thesurface of the support member 10. Specifically, in the later-describedcase in which the electronic part is detached from the aforementionedsupport member 10, it is preferred to use, for example, a stainlesssteel plate that has superior anticorrosion properties. On the otherhand, in the case that the electronic part is not detached from theaforementioned support member, in other words in the case that thesupport member is a substrate and an electronic part is formed on thesurface thereof, it is desirable that the support member be aninsulating member. On the surface 12, a electric power supply layer 13for allowing plating operation, which will be described later, isformed.

The configuration of the conductor portion 14 is not limited to acolumn-like shape standing on the surface 12, but variousconfigurations, such as a conductor portion composed of a wiring portionhaving a different thickness as shown in the drawing and column-likeconductor standing on the wiring portion, may be adopted.

Referring to the conductor 14, a resist film (not shown) is firstlyformed on the aforementioned surface 12. After that, holes correspondingto the aforementioned conductor portions 14 are formed on the resistfilm by photo etching. After the holes are formed on the resist film,the holse are subjected to a plating process, so that conductor metal isdeposited by electrolytic plating using the aforementioned electricpower supply film 13 as an electrode. With the above-described process,conductor portions 14 having the interior completely filled up andrising substantially vertically from the surface 12 can be formed. Inconnection with this, in the case that a conductor portion is composedof a wiring portion and a column-like conductor as described above,photo etching should be performed separately for the wiring portion andthe column-like conductor.

After the conductor portions 14 are formed on the surface 12 of thesupport member 10, a thermoplastic insulating sheet or a copper foil 18on which resin 16 is attached serving as a thermosetting insulatingsheet in a B-stage condition is caused to descend from above theconductor portions 14 along the direction indicated by arrow 20. Theaforementioned resin 16 may preferably be a thermoplastic resin compoundsuch as polyolefin, fluorocarbon resin, liquid crystal polymer,polyetherketone and polyphenylene sulfide or a thermosetting resin suchas a unsaturated polyester resin, polyimide resin, epoxy resin,bismaleimide triazine resin, phenol resin, polyphenylene oxide andpolyvinyl benzilether. The B-stage sheet refers to such a sheet that isin the state in which curing of the thermosetting resin is stoppedhalfway, and when heated further, it will be once melted and eventuallycured completely.

It is more preferable that the temperature in heating be higher than themelting point or softening point of the resin. On the side of the copperfoil that is opposite to the side on which the resin 16 is formed, thereis provided pressurizing means for pressing the copper foil 18 with theresin 16, although it is not shown in the drawings. Thus, it is possibleto press the copper foil 18 with the resin 16 against the support memberwhile heating it under a reduced pressure condition (namely, so-calledheat pressing under vacuum is performed).

When the copper foil 18 with the resin 16 is moved down in the directionindicated by arrow 20, the copper foil with the resin comes in contactwith the conductor portions 14. As the downward movement of the copperfoil 18 with the resin 16 further progresses, the resin 16 is pressed bythe conductor portions 14 to move in the directions indicated by arrows22 and the conductor portions 14 dent into the resin 16. FIG. 2A showsthis state. When the copper foil 18 with the resin 16 is further moveddown after the conductor portions 14 have dented into the resin 16, theconductor portions 14 dent into the resin further and eventually come incontact with the copper foil 16 as shown in FIG. 2B.

When the top of the conductor portions 14 comes in contact with thecopper foil 18, the conductor portions 14 function as a stopper toreceive the pressing force from the pressurizing means to stop thedownward movement of the pressurizing means. Upon detection of thestoppage of the downward movement of the pressurizing means, it isassumed that the conductor portions 14 have come in contact with thecopper foil 18, and the descending operation is terminated accordingly.The contact of the top of the conductor portions 14 and the copper foil18 is maintained until the resin 16 is cured. After the resin 16 hasbeen cured to form an insulating layer 24 surrounding the circumferenceof the conductor portions 14, the pressurizing means is moved awayupwardly. After that, the copper foil 18 is removed from the insulatinglayer 24, unused portions around the conductor portions 14 are cut off,and the conductor portions 14 and the insulating layer 24 are detachedfrom the surface of the support member 10. Thus, the height of theinsulating layer 24 can be made equal to the height of the conductorportions 14, and the thickness of the layer 28 in the electronic part 26can be made uniform as shown in FIG. 2C.

As described the above, according to the present invention, a layerhaving a uniform thickness is formed by forming conductor portions onthe surface of a support member, bringing an insulating sheet intocontact with the conductor portions from above, and pressing theinsulating sheet to the height of the conductor portions using theconductor portions as a stopper to make the height of the insulatingsheet equal to the height of the conductor portions, or a layer with auniform thickness including at least a conductor portions having theinterior completely filled up and rising vertically from the bottom ofthe body of a part and an insulating layer surrounding the circumferenceof the conductor portions and having a height equal to the height of theconductor portion is formed. Thus, it is possible to eliminateunevenness and control the layer thickness of an electronic partreliably. In addition, it is possible to reduce the resistivity of theconductor portions and to enhance the heat radiation effect.

1. A method for manufacturing an electronic part characterized by that alayer having a uniform thickness is formed by forming a conductorportion on a surface of a support member, bringing an insulating sheetinto contact with said conductor portion from above, and pressing saidinsulating sheet to the height of said conductor portion using saidconductor portion as a stopper to make the height of said insulatingsheet equal to the height of said conductor portion.
 2. A method formanufacturing an electronic part characterized by that a layer having auniform thickness is formed by forming a conductor portion on a surfaceof a support member, bringing an insulating sheet into contact with saidconductor portion from above, pressing said insulating sheet to theheight of said conductor portion using said conductor portion as astopper to make the height of said insulating sheet equal to the heightof said conductor portion, and then detaching said conductor portion andsaid insulating sheet from said surface.
 3. A method for manufacturingan electronic part characterized by that a layer having a uniformthickness is formed by forming a power supply film on a surface of asupport member, forming a conductor portion by plating using the powersupply film as an electrode, bringing an insulating sheet into contactwith said conductor portion from above, pressing said insulating sheetto the height of said conductor portion using said conductor portion asa stopper to make the height of said insulating sheet equal to theheight of said conductor portion, then detaching said conductor portionand said insulating sheet from said surface, and removing said powersupply film.
 4. A method for manufacturing an electronic part accordingto any one of claims 1 to 3, wherein a B-stage sheet is used as saidinsulating sheet.
 5. A method for manufacturing an electronic partaccording to any one of claims 1 to 3, wherein a thermoplasticinsulating sheet is used as said insulating sheet.
 6. A method formanufacturing an electronic part according to any one of claims 1 to 3,wherein heating is performed in addition to said pressing.
 7. Anelectronic part comprising, at least, a conductor portion having aninterior completely filled up and rising from vertically from a surfaceof a support member and an insulating layer surrounding thecircumference of said conductor portion and having a thickness equal tosaid conductor portion, said conductor portion and said insulating layerforming a layer having a uniform thickness.
 8. An electronic partcomprising, at least, a conductor portion having an interior completelyfilled up and rising from vertically from the bottom of a support memberand an insulating layer surrounding the circumference of said conductorportion and having a thickness equal to said conductor portion, saidconductor portion and said insulating layer forming a layer having auniform thickness.
 9. An electronic part according to claim 7 or 8,wherein said conductor portion is formed by plating.